1. Field of the Invention
The present invention concerns an alloplastic material for producing an artificial soft tissue component and/or for reinforcing a natural soft tissue component, for example a ligament, a tendon or a supporting tissue of a human or animal body.
The alloplastic material may be used in medicine and surgery, and be implanted into a human or animal body. In the following the term `body` will frequently be used to mean `human or animal body`. Similarly, the term `bundles` referring to components of the alloplastic material, will frequently be used to mean `one or more bundles`. The invention equally concerns a method for producing the alloplastic material of the invention.
2. The State of the Art
Artificial ligaments and tendons made of bundles interwoven or plaited, and consisting of plastic fibers or of carbon fibers coated with a substance absorbable inside the body are known in the art. The plastic fibers used for the purpose have been of thicknesses between 20 and 30 micrometers, whereas the carbon fibers used have been from 7 to 8 micrometers thick. Attention is called in this connection to the article titled "Implantatmaterialien fur den alloplatischen Bandersatz" by L. Claes, C. Burri and R. Neugebauer, which appeared in the 5th Series of Lectures of the Work Committee for Implants (5.Vortragsreihe des Arbeitskreises Implantate) dated Nov. 13, 1984, page 193 of the Deutscher Verband fur die Materialprufung e.v. Fibers made of plastic materials are subject, however, to strong aging effects within the body, probably caused, at least in part, by their absorbing water from body fluids. As time goes on, the plastic fibers may undergo the phenomenon known as creep, involving a slow change in length, a reduction in strength or mechanical resistance, and brittleness. The mechanical properties of carbon fibers used at present predominantly for implants are strongly non-isotropic, due to the graphitic structure of carbon. Bending loads or stresses with small radii of curvature, or even relatively slight shearing stresses, may cause fibers to fracture. This is confirmed by the cited publication of Claes et al. Furthermore, carbon fibers have only low ductility and tend to crumble, particularly if their coats have been dissolved after a longer stay inside the body.